人体β-珠蛋白基因5’旁侧调控元件与不同发育时期调控因子的相互作用

人β-珠蛋白基因主要在成年期的骨髓中表达,在胎儿肝,成年肝和K 562细胞中则处于关闭状态。凝胶电泳阻抑法分析发现,在人胎儿肝,成年肝及K 562细胞的核蛋白抽提物中存在着不同的与β-珠蛋白基因5'旁侧调控元件(-372到-194 bp)相结合的红系组织特异性的调控因子。竟争试验的结果表明,成年肝和K 562细胞中的调控因子与β-珠蛋白基因5'旁侧调控元件相互作用的方式具有一定的相似性,这两种细胞的调控因子既结合于负调控区(NCR 2)也结合于正调控区,说明两种细胞中β-珠蛋白基因的关闭机制可能是相似的。胎儿肝的核蛋白因子只结合于负调控区,推测在胎儿期存在独特的关闭机制。     

中国异皮属线虫一新种（线虫纲：垫刃目：异皮科）

本文描述采自河北省滦县寄生于白茅Ｉｍｐｅｒａｔｅ ｃｙｌｉｎｄｒｉｃａ ｖａｒ．Ｍａｊｏｒ的异皮属线虫一新种,中华异皮线虫Ｈｅｔｅｒｏｄｅｒａ ｓｉｎｅｎｓｉｓ ｓｐ．ｎｏｖ．;新种孢囊为柠檬形,阴门膜孔为两侧单膜孔型,下桥发达有泡状突;二龄幼虫口针基部球前部略凹陷,口孔侧唇外缘融合王头晕第１环纹内,即无明显侧唇,其体侧区有３条侧线与体环纹呈不完全网格状交叉;雄虫侧区有３条侧线与体环纹呈完全网格状     

湖北圆腹蛛一新种（蜘蛛目：球蛛科）

本文描述采自湖北省恩施和咸宁地区的球蛛科圆腹蛛属一新种－湖北圆腹蛛Ｄｉｐｏｅｎａ ｈｕｂｅｉｅｎｓｉｓ ｓｐ．ｎｏｖ．。     

慢性心功能不全大鼠心脏和血淋巴细胞β-肾上腺素受体的改变

在主动脉与肾动脉缩窄造成的慢性心功能不全大鼠,血浆儿茶酚胺浓度增高;心脏β-肾上腺素受体(β-AR)数量增加,其中β_1-AR及其mRNA增加,而β_2-AR及其mRNA不变;左心房异丙基肾上腺素(ISO)浓度-收缩效应曲线右移;而心肌ISO浓度-cAMP蓄积曲线无显著改变;血淋巴细胞β-AR数量显著减少.结果提示心功能不全时心脏β_1-AR数量增多,但其介导的正性变力效应反而降低,在cAMP生成以后的信号转导过程或心肌收缩成分功能存在障碍,而血淋巴细胞β-AR的改变与心脏β-AR的功能改变平行.     

苜蓿根瘤菌固氮酶基因启动子P1转录起始点下游顺序(DS)的特性

自生状态的苜蓿根瘤菌(Rhizobium meliloti)nifHDK操纵子的启动子P1能被微氧诱导而呈高水平表达,而fixABCX操纵子的启动子P2则呈微弱的表达.P1和 P2的 DNA顺序从转录起始点到上游-160处具有 85％的同源性,但从转录起始点到翻译起始点的核苷酸顺序则完全不同.用P1转录起始点下游从+17到+61核苷酸的DNA片段(DS)取代P2区的相应的DNA顺序,在自生状态微氧诱导条件下能提高P2的表达水平,在大肠杆菌中有NifA存在时P2亦呈高水平表达,说明P1和P2区的DS顺序是决定P1和P2自生状态微氧诱导条件下表达或异源表达差异的根本原因.在共生状态下P2的表达不依赖启动子下游顺序.采用引物延伸法测定 P2的转录起始点,发现 P2区当引入 P1区的 DS后不改变它的转录起始点.由于P2不论有DS的插入与否均不影响其在根瘤菌共生状态的正常表达,因此P2在自生状态的根瘤菌中与共生状态时的表达调节将有所不同.     

普通小麦与簇毛麦不对称体细胞杂交的研究

以不同浓度(0～2.5mmol/L)碘乙酰胺(IOA)处理的小麦(Triticum aestivum L.)原生质体为受体,以经6krad(130rad/min)⁶⁰Co-γ射线处理的继代后4～5d期簇毛麦(Haynaldia villosa)愈伤组织原生质体为供体,使用PEG法诱导细胞融合。融合细胞经培养形成细胞团、愈伤组织或植株。通过形态学比较、染色体检查及同工酶分析,确认了得到的愈伤组织和再生植株为体细胞杂种。     

食管癌病人运铁蛋白(Tf)和组特异性成份(Gc)亚型分布的研究

应用超薄层聚丙烯酰胺凝胶等电聚焦电泳法, 分析了潮汕地区216例无血缘关系、临床上诊断为食管癌的病人和216例健康人的运铁蛋白(Tf)亚型分布情况, 结果发现:食管癌病人组TfC1C1纯合子频率为0.2639,Tf*Cl基因频率为0.4745,显著低于正常人组(分别为0.4352和0.6227,均为P<0.0 01);同时,食管癌病人组TfC2C2纯合子频率为0.2278,Tf*C2基因频率为0. 4977,显著高于正常对照组(分别为0.1852,P<0.05,和0.3634,P<0.001)。应用超薄层聚丙烯酰胺凝胶等电聚焦结合免疫固定法,分析了潮汕地区21 7例无血缘关系的临床上诊断为食管癌病人和 217例健康人的组特异性成份(Gc)亚型的分布,发现两组间无显著性差异。     

Regulation of phospholamban and troponin-I phosphorylation in the intact rat cardiomyocytes by adrenergic and cholinergic stimuli: roles of cyclic nucleotides,calcium, protein kinases and phosphatases and depolarization

Protein phosphorylation was investigated in [³²P]-labeled cardiomyocytes isolated from adult rat heart ventricles. The -adrenergic stimulation (by isoproterenol, ISO) increased the phosphorylation of inhibitory subunit of troponin (TN-I), C-protein and phospholamban (PLN). Such stimulation was largely mediated by increased adenylyl cyclase (AC) activity, increased myoplasmic cyclic AMP and increased cyclic AMP dependent protein kinase (A-kinase)-catalyzed phosphorylation of these proteins in view of the following observations: (a) dibutyryl-and bromo-derivatives of cyclic AMP mimicked the stimulatory effect of ISO on protein phosphorylation while (b) Rp-cyclic AMP was found to attenuate ISO-dependent stimulation. Unexpectedly, 8-bromo cyclic GMP was found to markedly increase TN-I and PLN phosphorylation. Both ₁- and ₂-adrenoceptors were present and ISO binding to either receptor was found to stimulate myocyte AC. However, the stimulation of the ₂-AR only marginally increased while the stimulation of ₁-AR markedly increased PLN phosphorylation. Other stimuli that increase tissue cyclic AMP levels also increased PLN and TN-I phosphorylation and these included isobutylmethylxanthine (non-specific phosphodiesterase inhibitor), milrinone (inhibits cardiotonic inhibitable phosphodiesterase, sometimes called type III or IV) and forskolin (which directly stimulates adenylyl cyclase). Cholinergic agonists acting on cardiomyocyte M₂-muscarinic receptors that are coupled to AC via pertussis toxin(PT)-sensitive G proteins inhibited AC and attenuated ISO-dependent increases in PLN and TN-I phosphorylation. Thein vivo PT treatment, which ADP-ribosylated G_i-like protein(s) in the myocytes, markedly attenuated muscarinic inhibitory effect on PLN and TN-I phosphorylation on one hand and, increased the -adrenergic stimulation, on the other. Controlled exposure of isolated myocytes to N-ethyl maleimide, also led to the findings similar to those seen following the PT treatment. Exposure of myocytes to phorbol, 12-myristate, 13-acetate (PMA) increased the protein phosphorylation, augmenting the stimulation by ISO, and such augmentation was antagonized by propranolol suggesting modulation of the -adrenoceptor coupled AC pathway by PMA. Okadaic acid (OA) exposure of myocytes also increased protein phosphorylation with the results supporting the roles for type 1 and 2A protein phosphatases in the dephosphorylation of PLN and TN-I. Interestingly OA treatment attenuated the muscarinic inhibitory effect which was restored by subsequent brief exposure of myocytes to PMA. While the stimulation of alpha adrenoceptors exerted little effect on the phosphorylation of PLN and TN-I, inactivation of alpha adrenoceptors by chloroethylclonidine (CEC), augmented -adrenergically stimulated phosphorylation. KCl-dependent depolarization of myocytes was observed to potentiate ISO-dependent increase in phosphorylation (incubation period 15 sec to 1 min) as well as to accelerate the time-dependent decline in this phosphorylation seen upon longer incubation. Verapamil decreased ISO-stimulated protein phosphorylation in the depolarized myocytes. Depolarization was found to have little effect on the muscarinic inhibitory action on phosphorylation. Prior treatment of myocytes with PMA, was found to augment ISO-stimulated protein phosphorylation in the depolarized myocytes. Such augmented increases were completely blocked by propranolol. Forskolin also stimulated PLN and TN-I phosphorylation. Prior exposure of myocytes to forskolin followed by incubation in the depolarized and polarized media showed that PLN was dephosphorylated more rapidly in the depolarized myocytes. The results support the view that both cyclic AMP and calcium signals cooperatively increase the rates of phosphorylation of TN-I and PLN in the depolarized cardiomyocytes during -adrenergic stimulation. The results raise the additional possibility that the calcium signal may regulate the dephosphorylation of PLN in the depolarized cell. While muscarinic attenuation of -adrenergic action on protein phosphorylation was mediated, in part, by decreased AC activity, and muscarinic inhibition of AC and protein phosphorylation was not detectably influenced by the depolarization, the evidence was seen that muscarinic stimulation of dephosphorylation mechanisms are intimately involved. The postulate that the simultaneous stimulation of ₁-adrenoceptors inhibits -adrenergic stimulation of PLN and TN-I phosphorylation is supported.     

枯草杆菌蛋白酶E的156和165位突变

应用定点突变方法,在M222A突变的枯草杆菌蛋白酶E基因上进行E156S和V165I定点突变. 将突变基因插入大肠杆菌-枯草杆菌穿梭质粒pBE-2中,在碱性和中性蛋白酶缺陷型的枯草杆菌DB104中进行表达,得到突变种(M222A,E156S)和(M222A,E156S,V165I)蛋白酶E. 性质测定表明,E156S突变使蛋白酶比活力增加90%,并不影响酶的热稳定性和抗氧化性. 而V165I突变使蛋白酶比活力降低.